the carbonation oh hot meal
My kiln 4000t/d with preheater 5 stages, seperator calciner of Polysius. The carbonation of hot meal at the lowest cyclone is 75-80% and it is not stable. Sometime it has 65% and 90% (the temp. at meal chute is 860 degree) . My question is:
1. What is the factors influence on the carbonation of hot meal?
2. How is the way to improve the carbonation of hot meal (to 90% and stable)?
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re the carbonation oh hot meal
The main factors which can influence calcination degree for a kiln system such as yours are;-
- Variations in the chemistry, mineralogy and particle size distribution of the kiln feed. (this includes variations in the addition rate of any dust streams to the kiln feed) These factors can change the decarbonation temperature required.
- Unstable kiln feed rate.
- Unstable coal feed rate to the calciner burners.
- Unstable coal quality. (NCV, ash content, particle size etc)
- Periodic formation of buildups in the preheater/calciner which affect gas flows and/or affect heat exchange efficiency.
- Wear or buildups in or around your cyclone splash boxes which may reduce heat transfer from the gas stream to the hot meal.
- High CO levels at the kiln inlet.
- Any misalignment or fault with the main burner flame which may cause large variations in the kiln inlet temperature.
- Any misalignment or fault with the calciner burner(s).
- Variations in tertiary air quantity or temperature.
- A fault or failure of any preheater temperature control loops used in the kiln control system.
- Unstable feed rate or thermal energy content of any AFR (waste) streams fed to the preheater.
- Any change to hot meal sampling points or sampling and test methods
- Buildups around sample points can change the type of material sampled or periodically contaminate your hot meal sample with buildup material.
To improve your hot meal calcination degree you need to investigate these factors, identify which may apply to you and correct them.
Other participants may know of additional factors which you could investigate and I invite them to add to this list based on their knowledge and/or experience.